FUS
Intro
Minimalist programming language. Only knows how to create and modify data structures, which can be easily traversed by C code.
All values behave as if immutable. Behind the scenes, mutable values with copy-on-write semantics are guaranteed, making it possible to write performant purely functional programs without a fancy type system. In theory.
TODO: Fight Haskell and win.
Example
module fibonacci_generator:
def test of(->):
# Test basic generator behaviour
@new
dup @cur_index 0 == assert
dup @cur_value 0 == assert
@pop 0 == assert
@pop 1 == assert
@pop 1 == assert
@pop 2 == assert
@pop 3 == assert
@pop 5 == assert
@pop 8 == assert
@pop 13 == assert
dup @cur_index 8 == assert
dup @cur_value 21 == assert
drop
def test_cache of(->):
# The cache should let us do lookups of arbitrary indices
@new
# First call to @get does the calculations:
7 @get 13 == assert
# Second call to @get does a quick array lookup:
7 @get 13 == assert
drop
def new of(-> gen):
obj
0 =.i
0 =.a
1 =.b
# The cache starts off containing a and b:
arr 0, 1, =.cache
def cur_index of(gen -> i): .i
def cur_value of(gen -> val): .a
def next of(gen -> gen):
='gen
# Get variables from object members:
'gen .a ='a
'gen .b ='b
# Calculate next number in the sequence:
''a 'b + ='c
# Return modified generator:
''gen
# Increment the index:
..i 1 + =.i
# Push newest value onto the "cache" array:
..cache 'c, =.cache
''b =.a
''c =.b
def pop of(gen -> gen val):
dup @cur_value ='val
@next
''val
def get of(gen i -> gen val):
# Get "i"th value of Fibonacci sequence
='i ='gen
do:
# Loop while the requested index is not yet in cache:
'i ('gen .cache len) >= while
''gen @next ='gen
loop
# Quick lookup now that index is within cache:
'gen .cache 'i .$ ='val
# Return:
''gen ''val
# Run tests when module is loaded:
@test
Getting Started
Where stuff's at
The runtime is in src/*.[ch].
Various applications using the runtime are in src/main/*.c.
The compile script's first argument lets you choose which of these .c files to use.
Example fus programs are in fus/*.fus. They're not all guaranteed to work yet!
Tests which are guaranteed to work are in test/*.fus.
Usage
Compile & Run Test Suite:
./compile test && ./main
Compile & Run Parser:
# Parse a fus file:
./compile parse && ./main fus/sql.fus
# With ANSI colors!
./compile parse -DFUS_COLOR && ./main fus/sql.fus
Compile & Run "Runner":
# Parse and execute a fus file:
./compile run && ./main fus/fib.fus
# Parse and execute a fus file, dumping VM state:
./compile run && ./main -ds dsv fus/fib.fus
# NOTE: the -ds ("dump state") option takes an argument whose
# characters indicate what to dump:
# d - dump defs (function definitions)
# s - dump stack
# v - dump variables
# So, "-ds dsv" dumps defs, then stack, then variables,
# while "-ds s" just dumps stack, etc.
Compile & Run "Runner" on all test files in repo root:
# Roughly equivalent to:
# ./compile run && ./main test/*.fus
# ...except that ./main doesn't actually accept that syntax.
./run_test_files
Run all tests:
# Roughly equivalent to:
# ./compile test && ./main && ./run_test_files
./runtests
UWSGI plugin
What use is a language which can't be used as a web server?
Step 1: Write a plugin for UWSGI
Step 2: Write a web app
Possible next steps:
-
Generate HTML
-
Write a Redis client
-
Hook into more UWSGI features, like shared memory, caching, etc
In the Browser
Compiling fus with Emscripten turned out to be easier than I thought.
See the instructions for playing with this.
I guess TODO: Write a wrapper JS library (so you can map values between the two languages, etc).
Embedded in Python
Fus is now a Python C extension.
Its Python API is pretty lame minimalist:
from fus import run
# Example 1:
run(r' "Hello world!\n" str_p ')
# Example 2:
run("1 2 + p")
See the instructions for playing with this.
Also see the project on PyPi (and the project's source)!
So you can actually do pip install fus, which is sure to be useful in your own projects.
TODO: Improve the Python API, e.g. map values between the two languages.
Maybe something like: from fus import Value; v = Value('obj 1 =.x 2 =.y'); assert v.x == 1
